The Sky Blues sloppy defending and inability to handle Wellington's direct approach proved costly in their shock 3-1 home loss to the Phoenix at Jubilee Stadium on Saturday.

Phoenix had effectively wrapped the game at halftime, leading 3-0 by the break.

Sydney were also outplayed in the first half of last week's game against Central Coast, though they fought back to win after conceding the opening goal

Corica has fielded the same starting side for Sydney's last seven league and FFA Cup games, but after Saturday's match he committed to making changes for the ANZ Stadium clash with Western Sydney.

The only change Corica has made to his side this season was for the round two derby with the Wanderers, when he brought in Paulo Retre for Siem de Jong, who he wanted to rest before the FFA Cup final a few days later.

Ironically, de Jong injured a hamstring in a brief appearance off the bench and Retre has retained his run on spot ever since, with the Dutchman missing four games.

However, that could change next week, after Corica substituted Retre with de Jong at halftime on Saturday.

Daniel De Silva, who's made a number of cameo substitute appearances since recovering from a pre-season hamstring injury, is another option.

"We've got players back which is great, so there will be some changes next week," Corica said.

'We can't perform like that again. Our first half performances in the last two games were not good enough.

"The guys know that it's happened twice in a row, it needs to change a lot and it will next week.

"It's a derby game. We have good form against the Wanderers and we expect to win and put on a better performance."

Corica made it clear he wanted a greater defensive work rate across his side, not just from his back four.

"In attack as well, it's not just the defence, defence starts from the front, it's everyone," Corica said.

Sydney remain third but fell further behind the top two, Perth and Melbourne Victory, who later on Saturday helped out the Sky Blues by defeating the two sides just below them on the ladder.